Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany.
Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, 35043 Marburg, Germany.
Sci Adv. 2024 Aug 16;10(33):eado7729. doi: 10.1126/sciadv.ado7729. Epub 2024 Aug 14.
Nitrogenases are the only known enzymes that reduce molecular nitrogen (N) to ammonia. Recent findings have demonstrated that nitrogenases also reduce the greenhouse gas carbon dioxide (CO), suggesting CO to be a competitor of N. However, the impact of omnipresent CO on N fixation has not been investigated to date. Here, we study the competing reduction of CO and N by the two nitrogenases of , the molybdenum and the iron nitrogenase. The iron nitrogenase is almost threefold more efficient in CO reduction and profoundly less selective for N than the molybdenum isoform under mixtures of N and CO. Correspondingly, the growth rate of diazotrophically grown strains relying on the iron nitrogenase notably decreased after adding CO. The in vivo CO activity of the iron nitrogenase facilitates the light-driven extracellular accumulation of formate and methane, one-carbon substrates for other microbes, and feedstock chemicals for a circular economy.
固氮酶是唯一已知能够将分子氮（N）还原为氨的酶。最近的研究结果表明，固氮酶也能还原温室气体二氧化碳（CO），这表明 CO 是 N 的竞争者。然而，迄今为止，还没有研究无处不在的 CO 对 N 固定的影响。在这里，我们研究了两种固氮酶——钼固氮酶和铁固氮酶对 CO 和 N 的竞争还原。在 N 和 CO 的混合物中，铁固氮酶在 CO 还原方面的效率几乎是钼同型物的三倍，而对 N 的选择性则低得多。相应地，依赖铁固氮酶的固氮菌的生长速率在添加 CO 后明显下降。铁固氮酶的体内 CO 活性促进了光驱动的胞外积累甲酸盐和甲烷，这是其他微生物的一碳底物和循环经济的原料化学品。
